Cartridge fuse



June 1,1932, @A JQHNSO 1,861,744

CARTRIDGE FUSE Filed Oct. 26. 1927 Patented `une 7, 1932 UNITED STATES PATENT OFFICE CHESTER A. JOHNSON, OF CHICAGO, ILLINOIS, ASSIGNOR TO JEFFERSON ELECTRIC y COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS CARTRIDGE FUSE Application filed October 26, 1927, Serial No. 228,713.

The invention pertains generally to cartride fuses and relates more particularly to cartridge fuses of the so-ca-lled knife blade type in'which the fusible element is renewable, the general object of the invention being to produce a new and improved fuse of this type especially adapted to save time and labor in the disassembling and reassembling of the parts in the process of renewal of a fusible element.

Another object of the invention is to provide an improved fuse of this character in which all of the parts separable from the casing are incorporated in a single unit thus Vproviding a two part fuse.

Another object of the invention is to provide an improved cartridge fuse embodying few and simple parts readily separable to permit of replacing the fusible element and which may be conveniently and quickly assembled to form an exceedingly rigid and rugged structure.

A further object is to provide such a fuse with novel means for securing a terminal blade detachably to the casing.

Other object-and advantages will become apparent in the following description taken in conjunction with the accompanying drawing, in which:

Figure 1 is a longitudinal View partly in central section of one 'form of the invention.

Fig. 2 is a similar view taken in a plane at riht angles to that of Fig. 1.

igs. 3 and 4 are elevational and plan views -respectively of the terminal blade unit.

Figs. 5 and 6 are views taken in the plane of the lines .5-5 and 6-6 respectively oi" Fig. 2.

Fig. 7 is a View in perspective of a preferred means for securing a terminal blade to the insulating bar.

Although the invention is susceptible of vvarious modifications and alternative constructions, I will show and herein describe in detail the preferred embodiment, but it is to be understood that I do not thereby intend to limit the invention to the specific form disclosed-but intend to cover all the modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

1n the exemplary form illustrated herein ,the invention embodies a casing comprising a cylindrical tube 10 of suitable insulating material7 such as libre, and two metallic heads or bushings 11, 12 secured to the ends thereoil in any preferred manner. As shown herein the head 11 is provided with an inwardly eX- tending end wall 13 which forms a trans-` verse closure across the head 11. rll`he other head has a plurality of webs 14 defining a substantiall rectangular aperture 15 in the head 12. .gs viewed in Figs. 1 'and 2 the transverse wall 13 is shown upon the right hand head and the webs 14 and the angular aperture 15 upon the lett hand head of the casing 10. rllhe transverse wall '13 has therein a diametrical slot 16 and a pair of apertures 17 spaced equidistantly upon either side of the slot 16 on the diametrical line substantially perpendicular thereto. The head 11 which is provided with the transverse wall carries an end cap 18 secured thereon in any suitable manner which permits relative rotation therebetween, In this instance this is accomplished by providing an annular groove 19 in the head 11 having a portion of the metal end cap 18 swedged into said groove at a plurality of points. The iat end wall of the end cap 18 which abuts the wall 13 has therein a pair of slightly arcuate key hole slots 2O (Fig. 5) adapted to register with the apertures 17 in the walls and a central diametrical slot 21 formed to permit limited rotation of said end cap about a terminal blade member extending therethrough. 1n the present instance the slot 21 is formed by removing diametrically opposed sectors of the cap. The l' registering slots and apertures in the transverse wall 13 and the end cap 18 permit passage therethrough of one end of the terminal blade unit as will be presently described.

The terminal blade unit, in the form shown herein, comprises a pair of terminal blades 22, 23 one of which carries a ledge 24 having means for seeurlng that blade in position in the casing and the other blade having a ledge 25 adapted to register in the aperture 15 of the head 12. A fusible element 26 connects the blades and an insulating bridge section, comprising a pair of metallic clips 27 permanently secured to the blades and joined by an insulating member or bar 28, secures the blades rigidly together in spaced relation. A disk or washer 29 and an end cap 30 are permanently carried upon one of the blades. As shown, the inner ,portions of the blades are narrower than the outer to provide shoul ders 31 against which the ledges abut.

The ledges 2 4, 25 preferably comprise small substantially square plates having central slots therein which may be slipped over the narrower ends of the blades to abut the shoulders 31 and to be permanently secured in such position, as by soldering. The size of the ledges is substantially the same as that of the aperture 15 provided by the webs 14 in the `head 12. As may be seen in Fig. 6, the slot- 32 in the ledge 25 mounted upon the left hand blade 23 extends thereacross parallel to two edges of the ledge so that the ledge will be positioned squarely upon the blade.

This leaves a part of the shoulder 31 projectj ing beyond the edges of the ledge 25, as shown F in Fig. 1. The ledge 24 upon the opposite pin 33 rigid therewith for a purpose which will hereafter become apparent.

The diskf29 and the end cap 30 carriedby the blade 23 are loosely but permanently mounted thereon, the disk for sliding move- .ment relative to the blade and the end cap for both sliding and rotational movement. Preferably the permanent mounting. is accomplished by means of one or more projecting or upset portions 34 on the blade, which portions also limit the extent of the sliding movement of the disk and the end cap. The endf pair engages the sides of said blade. Preferably the edges of the blade are recessed to receive the flanges l36 and 37 which are rigidly secured thereto, as by soldering. The free end of the clip is provided with a pair of side flanges 38 outstanding from the plate 35 in the opposite direction from the fiauges 36 and 37. The side ianges 38 provide a channel or trough to receive the ends ofthe insulating bar 28 which may be secured therein in any suitable manner as by screws 39 extending through the insulating bar 28 into threaded engagement with an opening 40a in the clip.

j Means for detachably securing the fusible element 26 intermediate the blades 22, 23 com prises herein a bolt 40 for each blade which extends through registering apertures in the blades, clips and fusible element to be engaged by a nut 41. As shown the position of the bolts 40 through the clips and blades are such as to locate the peripheryi of the nut 41 immediately adjacent the ends of the insulating bar 28 whereby the bar will engage a faeeof the headof the nut to prevent turning thereof. Thus the bolt 40 may be conveniently loosened by a single tool to permit replacement of the fusible element. When the bridge structure is assembled the terminal blade unit presents a perfectly rigid member adapted to be readily inserted or Withdrawn v from the casing.

In assembling the fuse, considering the terminal blade unit as being complete as shown in Figs. 3 and 4, it is only necessary to insert the unit into the casing through the aperture 15 in the head 12. The blade 22 is then inserted in the registered slots 16 and 21 in the transverse wall 13 and end cap 18 respectively with the headed pins 33 on the ledge 24 projecting through the apertures 17 and the key hole slots 20. A slight rotation of the end cap 18serves to engage the narrower portions of the key hole slots about the Shanks of the headed pins 33 and provides what may f be termed a locking device to secure the one end of the unit in the casing. During the movement of the terminal blade 22 `into its final or locking position, the ledge 25 on the opposite blade 23 becomes positioned in the plane of the webs 14 which define the rectangular opening 15 in the head with the shoulders 31 abutting the webs. The end cap 30 is then screwed onto the head 12 drawing the disk 29 into close abutment with the webs 14 and the ledge 25.

Disassembly of the fuse to replace or renew a fusible link is quite as easily accoml plished. The end cap 30 is unserewed from the head 12, the opposite end cap 18 is rotated to release the headed pins 33 from engagement with the keyhole slots 20 and the terminal blade unit may be withdrawn from the casing. v

It Will be apparent from the foregoing del scription that a fuse has been provided in which all of the component .parts thereof have been incorporated into two readily sepasembled and reassembled with ease and ra pidity; in which the terminal blades are locked in the casing by positive mechanical means; and in which all of the parts are permanently secured in one of two units thereby Ipreventing the loss or misplace-.ment of some part of the fuse. Furthermore, a structure has been provided in which the elements when assembled are combined into an inherently rigid unit, since movement of the terminal blades rotationally, transversely or longitudinally of the casing is positively prevented.

I claim as my invention:

l. A two part renewable cartridge fuse having, in combination, a casing, a head closing one end of said casing provided with a diametrical slot and an eccentric aperture, a rotatable end cap carried by said headhaving a diametrical slot and a' keyhole..slot arranged to register with said slot and aperture in said head, an externally screw threaded head on the other end of said casing having a substantially rectangular opening therein, and a terminal blade unit adapted to be mounted in said casing comprising a pair of terminal blades, a fusible link detachably secured therebetween, an insulating bridge section spacing one blade from the other and providing with said blades a substantially rigid unit, a pair of headed pins carried by one bladeI adapted to engage said aperture and keyhole slot when said blade is inserted in the registering slots in said head and end cap and to beheld thereon by engagement between said pins and key hole slots upon rotation of said end cap, an angular ledge on the other blade, an internally screw threaded end cap permanently mounted for rotation on said blade, and a disk slidable on said blade between said ledge and said end cap on said blade, said lledge being adapted to fit snugly within the rectangular opening in saidlast mentionedhead with said disk in abutting relation thereto when said end cap on the blade is screwed onto the externally threaded head.

2. A renewable cartridge fuse comprising, in combination, a tubular casing havin metallic heads secured to the ends thereo and a terminal blade locking means erm-anently and rotatably mounted on one o? said heads, a pair of terminal blades secured rigidly together in spaced relation by means of an insulating bridge section and arranged to be inserted in and withdrawn 'from said casing as a through the other head, a locking `device mounted rigidly on one blade arranged to extend beyond the one head and into engagement with said locking means, means on the other blade arranged to engage the other head to prevent rotational movement of the blade in the casing, and means permanently and rotatably mounted on said other blade adapted to be detachably engaged to said other head to close that end of the casing and to.secure that blade in position.

3. A renewable cartridge fuse having, in combination, a tubular casing, a metallic head secured to one end thereof, said head having a transverse wall with a terminal blade receiving slot therein, a unitary terminal blade structure arranged to be inserted in said casing from the other end thereof, said structure including a blade having a portion of uniform cross section extending outwardly from said wall, a device carried on said blade arranged to project through an eccentric aperture in said wall, and an end cap rotatably mounted on said headyarranged to engage said device to secure said blade against longitudinal movement.

4. A renewable cartridge fuse having, in combination, a tubular casing, metallic heads Secured to the ends thereof, a terminal blade unit including a pair of terminal blades and an insulating bridge section securing said blades togetherin spaced relation, a locking device carried on one blade adapted to eX- tend beyond one head, an end cap permanently and rotatably mounted on said head arranged to interengage with said device to prevent longitudinal movement of the blade, and means permanently mounted on the other blade for securing said blade to the casing and closing that end of the casing.

5. A renewable cartridge fuse having, in combination, a terminal blade unit including a pair of terminal blades and an insulating bridge section rigidly secured to and spacing said blades apart, anda detachable tubular casin having an end closure arranged to4 permit a blade to extend therethrough, means permanently mounted on said end of the casing, means carried on and in spaced relation to said blade adapted to be detachably engaged by said means on said casing to prevent longitudinal movement of the blade, the other of' said blades having a closure for the other end of said casing permanently carried on said blade.

6. A renewable cartridge fuse comprising a casing having an integral transverse wall at one end with a terminal blade receiving slot therein, and a terminal blade .unit adapted to be inserted into said casing from the opposite end thereof, said unit including two blades, one of which is adapted to be inserted through said slot and the other having a closure for the other end of said casing permanently mounted thereon, said one blade having interlocking means spaced fromsaid blade on opposite sides thereof, said casing includother end of said casing mounted on oneblade, and means on the other blade adapted to engage said key hole slots when said blade is inserted in said diametrical slot in said first mentioned closure, said second mentioned closure being arranged todetachably engage said casing to prevent displacement of said unit therefrom.

8. A two part renewable cartridge fuse having, in combination, a casing and-a terminal blade unit including a pair of terminal blades, said casing having one permanently closed end provided with a slot adapted snugly to receive one of the terminal blades and to hold said blade against relative rotation, means providing an interlocking engagement between said casing and said blade to prevent relative longitudinal movement therebetween, said terminal bladeunit also having an end cap permanently mounted upon the second blade adaptedto close the other end of the casing and to detachably secure said unit rigidly therein.

9. A renewable cartridge fuse comprising, in combination, a casing having atransverse Wall at one end with an opening therein, and a terminal blade unit including two blades,

said opening in the closed end of said casing having a contour snugly to receive one of said blades therethrough, the other of said blades having a closure for the other end of said therein to receive said locking means and the blade associated therewith, means on said casing movable into engagement with said locking means rigidly to secure that blade on the casing, and means for securing the other of said terminal blades to the other end of said casing.

In testimony whereof, I have hereunto aiiixed my signature.

CHESTER A. JOHNSON.

casing permanently mounted thereon, each of said blades having positive casing engaging means thereon detachably to secure said terminal unit rigidly in said casing.

10. A renewable cartridge fuse having, in combination, a terminal blade unit including a pair of terminal blades and an insulating bridge section rigidly secured to andv spacing said blades apart, and a casing for said unit, said casing having a closure permanently mounted on one end comprising two relatively movable parts, one of which is adapted detachably to engage one of said blades, the other of said blades having a closure for the other end of said casing permanently carried by said blade.

11. A renewable cartridge fuse comprising, in combination, a casing having a transverse wall at one end, a terminal blade unit V including two blades, locking means carried on one of said blades in spaced relation thereto, said transverse wall having openings 

